1. Field of the Invention
The invention is related to a ski brake that is adapted to brake the movement of a ski, especially an alpine ski, in case the boot which is retained on the ski is released. The invention is also related to a ski equipped with the device or the brake mentioned hereinabove.
The invention is also related to a device whose object is to modify the natural pressure distribution of a ski, such as especially an alpine ski, over its sliding surface.
2. Description of Background and Relevant Information
Skis that are used for alpine skiing are constituted by relatively long members, the boots of the skier being retained thereupon by front and rear binding elements. The boots and the binding elements are located approximately in the median zone of the ski, which is commonly known as the middle sole. The skis themselves possess a natural arch at rest, whereby the middle sole is naturally raised with respect to the front end of the ski or spatula, and the rear end of the ski or heel. In addition, the skis possess a flexibility, which is a function of their internal structure. During skiing, the ski deforms elastically in response to the various stresses to which it is subject from the skier, and from the terrain on which it slides.
The main forces to which a ski is subjected are constituted by the weight of the skier and by the reaction to which the sliding surface subjects the ski.
The ski is also biased by the binding elements. It is, in fact, known that the binding elements pinch the boot along a longitudinal direction. The reaction to this pinching action is transmitted by the binding elements to the ski. This reaction, however, differs in nature according to the assembly mode of the rear binding element to the ski. Indeed, some rear binding elements are directly assembled to the ski, whereas others are assembled on the front binding element by a non-extensible link, such as a metallic plate which extends beneath the boot.
The ski is also influenced by the position of the skier on his or her boots, depending on whether his or her weight is carried towards the front or towards the rear.
It is known that the behavior of the ski on snow can be modified, especially the ease with which it handles turns, and the quality of its movements in turns, or in a straight line, by influencing the arch of the ski, or else by playing with the longitudinal pressure distribution of the ski on the snow. By playing with this pressure distribution, it is known that the ski can be rendered more or less pivotal or more or less guiding, i.e., one can promote its ability to turn easily or to display great stability of movement. In currently available skis, the pressure distribution of the ski on the snow is determined mainly by the internal structure of the ski and by the assembly mode of the binding elements to the ski, that is, with or without the connection plate between the front and rear elements. Pressure distribution can also be influenced by the intensity of the thrust that is provided to the return springs.
There exist devices with attached elements that enable the pressure distribution of the ski on the snow to be modified. As such, European Patent Application No. 183,586 describes a plate of an elastic material of a spring blade type attached above the ski, between the binding elements and the ski. This blade has cursors at the level of its front and rear ends, by virtue of which a part of the forces to which the ski is subject are transmitted vertically. This device, however, has a disadvantage of providing only mediocre performance and it is very cumbersome. It is adapted for cases where both feet of the skier are in support on the same ski, so as to avoid the entire weight of the skier from being concentrated in the middle sole zone. On the other hand, it is ill-adapted to cases where a pair of traditional skis are used.
Also known, as exemplified by European Patent Publication No. 409,749, is a device constituted by a plate which is raised with respect to the upper surface of the ski and is maintained between two longitudinal abutments. The elastic shock absorption means are positioned between the plate and the abutments, and the pre-stress exerted on such elastic means is adjustable. As for the bindings, they are assembled on the plate. This device provides good results, but its disadvantage is that the binding elements are affixed to the attached plate and not to the ski itself.
Other devices of the same type are described for example in U.S. Pat. No. 2,560,693 and the German Patent No. 2,259,375.
It must be noted that in these devices, the pre-stress that the attached element induces on the ski itself cannot be eliminated. This pre-stress affects the ski, even in the absence of the boot and even when the skis are stored. The ski is therefore continually subject to a stress that affects its flexion, even at rest. It can thus be subject to an irreversible deformation due to this pre-stress.
In addition, these devices are provided to be equipped with standard binding and braking elements. In particular, there is no provision for specific brake arrangements that take into account the presence of the element that has been attached onto the ski.
Skis usually used for skiing are indeed most often equipped with a brake that is intended to brake the movement of the ski in case of accidental release of the boot.
The brake includes two braking arms movable between a working position, wherein they project beneath the sole of the ski, and a resting position wherein they rise above the ski.
A spring or an elastic return means elastically returns the braking arms into the working position.
Generally, the brake is associated with the rear binding element, i.e., the base of the brake which bears the arms continuously extends the base of the rear binding element.
Currently known brakes are automatic, i.e., the movement of the braking arms is directly influenced by the engagement of the boot in the binding elements, or else by the accidental or voluntary disengagement of the boot from the binding elements.
The control or influence means are most often a foot or sole-engaging pedal which projects above the upper surface of the ski. When the boot is engaged in the binding elements, this pedal is pressed against the upper surface of the ski.
Such brakes are known, for example, from U.S. Pat. Nos. 3,989,271 or 4,123,083.
The space requirement of these brakes on the ski is not substantial, such that they do not exert a stiffening action on the structure of the ski, or exert a negligible action as little as possible.
In addition, a disadvantage of these known brakes is the presence of increased friction between the sole-engaging pedal and the boot. Indeed, certain brakes provide a very substantial resistance upon engagement of the boot in the binding elements.